What term describes the ability of an aircraft to return to equilibrium after a disturbance?

• A. Stability
• B. Maneuverability
• C. Controllability
• D. Trim

Answer: (A)

Stability is about how an aircraft behaves when it’s nudged away from its trimmed, steady flight condition. If a gust or a disturbance pushes the airplane off equilibrium, a positively stable aircraft tends to develop restoring forces and moments that bring it back toward that original condition. Static stability describes the initial tendency to return, while dynamic stability describes how the motion settles over time. If stability is positive, the airplane returns to level flight; if it’s negative, it tends to move farther away; if it’s neutral, it stays where it’s pushed.

This idea is different from maneuverability, which is how easily the airplane can be steered or angled during flight; controllability, which is about the ability to achieve a desired state with the available controls (and can be affected by system faults); and trim, which is the steady, unaccelerated condition the aircraft holds with no ongoing control input. So the term that describes the ability to return to equilibrium after a disturbance is stability.